| Re: image interplate and overlay lat/lon? [message #81175] |
Wed, 22 August 2012 10:13  |
beardown911
Messages: 21
Registered: March 2007
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Junior Member |
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On Wednesday, August 22, 2012 10:57:48 AM UTC-5, go cats wrote:
> Hello all,
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>
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> My goal is to take an image(s) and overlay geographic lat/lon information onto the image. I have lat/lon information of four boundaries and tried to create a regular grid using them.
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> I’ve used David’s code to generate a regular lat/lon grid, and tried to interpolate image with gridded lat/lon data.
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> However, outImage looks blank and only geographin lat/lon data are shown with 0 image pixel values. I am working on 8-bit tif images.
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> Would anybody give me some tips how to make this work or what I did wrong?
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> Thanks in advance,
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> Kim
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> P.S. Below is what I've been working on.
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> ;---------------------------------------------------------
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> ; image(0,0)locates at the upper left corner
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> xOrigin = maxLon
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> yOrigin = maxLat
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> xscale = (maxLon – minLon)/nS
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> yscale = (maxLat – minLat)/nL
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> uvec = Findgen(nS) * xscale + xOrigin
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> vvec = yOrigin - (Findgen(nL) * yscale)
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> uarray = Rebin(uvec, nS, nL)
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> varray = Rebin(Reform(vvec, 1, nL), nS, nL)
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> outImage = Interpolate(inImage, varray, uarray)
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> .
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> .
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> .
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> geoTag = { $
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> ModelTiepointTag: [0.0, 0.0, 0.0, xOrigin, yOrigin, 0.0], $
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> ModelPixelScaleTag: [xscale, yscale, 0.0], $
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> GTModelTypeGeoKey: 2, $ ; (ModelType Geographic)
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> GTRasterTypeGeoKey: 2, $ ; (RasterPixelIsPoint)
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> GeographicTypeGeoKey: 4326 $ ; (WGS84)
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> }
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> .
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> .
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> WRITE_TIFF, outImage, GEOTIFF = geoTag
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> ;-----------------------------------------------------
Thanks David for your prompt answer and guide.
Yes, as you pointed, no interpolate is needed for the input image.
Image array and lat/lon grids have the same size.
I'll read through "Map Structures" and try it.
Thank you again and have a nice day!
Kim
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